1. Field of the Invention
The invention relates to a linear actuator which includes a quick release mechanism.
2. The Prior Art
A quick release unit in an actuator is used for temporarily interrupting the connection to the inert part of the transmission and the motor so that the activating element may be adjusted manually. As an example of where a quick release unit is used, reference may be made to hospital beds, patient lifters, emergency exits or fire doors, and other structures where it is important, if not vital, to be able to make a spontaneous adjustment of the activating element.
Actuators having a quick release function are known inter alia from EP 685 662 B1 and WO 03/033946 A1 to Linak A/S. The two documents relate to a quick release unit based on two cylindrical elements wound with a releasable coupling spring. The structures are excellent as far as they go, but they occupy some space, partly because the coupling spring is to have a certain length, and partly because the release mechanism is also bulky.
For the sake of completeness, it may be mentioned that EP 577 541 B1 to Linak A/S discloses another quick release unit with two angularly positioned gear wheels, where the one gear wheel may be displaced out of engagement.